I've been trying out the Linux Mint live disc for a couple of days now, and I like it a lot! I'm hoping to do a dual boot on my laptop soon.

I installed VLC Media Player and had it stream a file off of my home theater pc. It worked fine 'til I started messing around with some settings, then it froze up. I had the player and preferences windows open and they wouldn't respond to anything besides minimizing/maximizing.

In Windows, I could Control+Alt+Delete, then "End Task" an unresponsive program and that would (usually) take care of things.

You can end tasks from the system monitor.
Go to the mintmenu and then Administration and finally System Monitor
or
Right click on the taskbar and Add to panel... System Monitor

Once the system monitor is open click the Processes tab and then right click on the process you wish to end or kill.

End process will try and gracefully end the process, kill is for when you cannot end the task. If you encounter a problem where you are unable to even get to the system monitor try this.

Press CTRL + ALT + F1 this will bring you to an alternate command prompt, use you normal login here. Once logged in type:
pgrep "process name"
where "process name" is the program you wish to end. For example if firefox locked up type:
pgrep firefox
This will return a process ID, to end that process type:
kill 12345
where 12345 is the number returned from the previous command.

If you don't know the name of the process you are looking for, try this instead:
ps aux | more
(the | is not the letter L or the letter I or the number 1, but the "pipe" command it is located above on the same key as "\" on a US keyboard.
You can browse through this list and then kill the process ID as in the previous example.

When you are done with the command line, press CTRL + ALT + F7 to return to you normal login.